package org.g4studio.core.mvc.xstruts.upload;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.Serializable;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.List;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;

import org.apache.commons.fileupload.DiskFileUpload;
import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItem;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.g4studio.core.mvc.xstruts.Globals;
import org.g4studio.core.mvc.xstruts.action.ActionMapping;
import org.g4studio.core.mvc.xstruts.action.ActionServlet;
import org.g4studio.core.mvc.xstruts.config.ModuleConfig;

/**
 * <p>
 * This class implements the <code>MultipartRequestHandler</code> interface by
 * providing a wrapper around the Jakarta Commons FileUpload library.
 * </p>
 * 
 * @version $Rev: 421119 $ $Date: 2006-07-11 21:49:11 -0700 (Tue, 11 Jul 2006) $
 * @since Struts 1.1
 */
public class CommonsMultipartRequestHandler implements MultipartRequestHandler {
	// ----------------------------------------------------- Manifest Constants

	/**
	 * <p>
	 * The default value for the maximum allowable size, in bytes, of an
	 * uploaded file. The value is equivalent to 250MB.
	 * </p>
	 */
	public static final long DEFAULT_SIZE_MAX = 250 * 1024 * 1024;

	/**
	 * <p>
	 * The default value for the threshold which determines whether an uploaded
	 * file will be written to disk or cached in memory. The value is equivalent
	 * to 250KB.
	 * </p>
	 */
	public static final int DEFAULT_SIZE_THRESHOLD = 256 * 1024;

	// ----------------------------------------------------- Instance Variables

	/**
	 * <p>
	 * Commons Logging instance.
	 * </p>
	 */
	protected static Log log = LogFactory.getLog(CommonsMultipartRequestHandler.class);

	/**
	 * <p>
	 * The combined text and file request parameters.
	 * </p>
	 */
	private Hashtable elementsAll;

	/**
	 * <p>
	 * The file request parameters.
	 * </p>
	 */
	private Hashtable elementsFile;

	/**
	 * <p>
	 * The text request parameters.
	 * </p>
	 */
	private Hashtable elementsText;

	/**
	 * <p>
	 * The action mapping with which this handler is associated.
	 * </p>
	 */
	private ActionMapping mapping;

	/**
	 * <p>
	 * The servlet with which this handler is associated.
	 * </p>
	 */
	private ActionServlet servlet;

	// ---------------------------------------- MultipartRequestHandler Methods

	/**
	 * <p>
	 * Retrieves the servlet with which this handler is associated.
	 * </p>
	 * 
	 * @return The associated servlet.
	 */
	public ActionServlet getServlet() {
		return this.servlet;
	}

	/**
	 * <p>
	 * Sets the servlet with which this handler is associated.
	 * </p>
	 * 
	 * @param servlet
	 *            The associated servlet.
	 */
	public void setServlet(ActionServlet servlet) {
		this.servlet = servlet;
	}

	/**
	 * <p>
	 * Retrieves the action mapping with which this handler is associated.
	 * </p>
	 * 
	 * @return The associated action mapping.
	 */
	public ActionMapping getMapping() {
		return this.mapping;
	}

	/**
	 * <p>
	 * Sets the action mapping with which this handler is associated.
	 * </p>
	 * 
	 * @param mapping
	 *            The associated action mapping.
	 */
	public void setMapping(ActionMapping mapping) {
		this.mapping = mapping;
	}

	/**
	 * <p>
	 * Parses the input stream and partitions the parsed items into a set of
	 * form fields and a set of file items. In the process, the parsed items are
	 * translated from Commons FileUpload <code>FileItem</code> instances to
	 * Struts <code>FormFile</code> instances.
	 * </p>
	 * 
	 * @param request
	 *            The multipart request to be processed.
	 * @throws ServletException
	 *             if an unrecoverable error occurs.
	 */
	public void handleRequest(HttpServletRequest request) throws ServletException {
		// Get the app config for the current request.
		ModuleConfig ac = (ModuleConfig) request.getAttribute(Globals.MODULE_KEY);

		// Create and configure a DIskFileUpload instance.
		DiskFileUpload upload = new DiskFileUpload();

		// The following line is to support an "EncodingFilter"
		// see http://issues.apache.org/bugzilla/show_bug.cgi?id=23255
		upload.setHeaderEncoding(request.getCharacterEncoding());

		// Set the maximum size before a FileUploadException will be thrown.
		upload.setSizeMax(getSizeMax(ac));

		// Set the maximum size that will be stored in memory.
		upload.setSizeThreshold((int) getSizeThreshold(ac));

		// Set the the location for saving data on disk.
		upload.setRepositoryPath(getRepositoryPath(ac));

		// Create the hash tables to be populated.
		elementsText = new Hashtable();
		elementsFile = new Hashtable();
		elementsAll = new Hashtable();

		// Parse the request into file items.
		List items = null;

		try {
			items = upload.parseRequest(request);
		} catch (DiskFileUpload.SizeLimitExceededException e) {
			// Special handling for uploads that are too big.
			request.setAttribute(MultipartRequestHandler.ATTRIBUTE_MAX_LENGTH_EXCEEDED, Boolean.TRUE);

			return;
		} catch (FileUploadException e) {
			log.error("Failed to parse multipart request", e);
			throw new ServletException(e);
		}

		// Partition the items into form fields and files.
		Iterator iter = items.iterator();

		while (iter.hasNext()) {
			FileItem item = (FileItem) iter.next();

			if (item.isFormField()) {
				addTextParameter(request, item);
			} else {
				addFileParameter(item);
			}
		}
	}

	/**
	 * <p>
	 * Returns a hash table containing the text (that is, non-file) request
	 * parameters.
	 * </p>
	 * 
	 * @return The text request parameters.
	 */
	public Hashtable getTextElements() {
		return this.elementsText;
	}

	/**
	 * <p>
	 * Returns a hash table containing the file (that is, non-text) request
	 * parameters.
	 * </p>
	 * 
	 * @return The file request parameters.
	 */
	public Hashtable getFileElements() {
		return this.elementsFile;
	}

	/**
	 * <p>
	 * Returns a hash table containing both text and file request parameters.
	 * </p>
	 * 
	 * @return The text and file request parameters.
	 */
	public Hashtable getAllElements() {
		return this.elementsAll;
	}

	/**
	 * <p>
	 * Cleans up when a problem occurs during request processing.
	 * </p>
	 */
	public void rollback() {
		Iterator iter = elementsFile.values().iterator();

		while (iter.hasNext()) {
			FormFile formFile = (FormFile) iter.next();

			formFile.destroy();
		}
	}

	/**
	 * <p>
	 * Cleans up at the end of a request.
	 * </p>
	 */
	public void finish() {
		rollback();
	}

	// -------------------------------------------------------- Support Methods

	/**
	 * <p>
	 * Returns the maximum allowable size, in bytes, of an uploaded file. The
	 * value is obtained from the current module's controller configuration.
	 * </p>
	 * 
	 * @param mc
	 *            The current module's configuration.
	 * @return The maximum allowable file size, in bytes.
	 */
	protected long getSizeMax(ModuleConfig mc) {
		return convertSizeToBytes(mc.getControllerConfig().getMaxFileSize(), DEFAULT_SIZE_MAX);
	}

	/**
	 * <p>
	 * Returns the size threshold which determines whether an uploaded file will
	 * be written to disk or cached in memory.
	 * </p>
	 * 
	 * @param mc
	 *            The current module's configuration.
	 * @return The size threshold, in bytes.
	 */
	protected long getSizeThreshold(ModuleConfig mc) {
		return convertSizeToBytes(mc.getControllerConfig().getMemFileSize(), DEFAULT_SIZE_THRESHOLD);
	}

	/**
	 * <p>
	 * Converts a size value from a string representation to its numeric value.
	 * The string must be of the form nnnm, where nnn is an arbitrary decimal
	 * value, and m is a multiplier. The multiplier must be one of 'K', 'M' and
	 * 'G', representing kilobytes, megabytes and gigabytes respectively.
	 * </p>
	 * <p>
	 * If the size value cannot be converted, for example due to invalid syntax,
	 * the supplied default is returned instead.
	 * </p>
	 * 
	 * @param sizeString
	 *            The string representation of the size to be converted.
	 * @param defaultSize
	 *            The value to be returned if the string is invalid.
	 * @return The actual size in bytes.
	 */
	protected long convertSizeToBytes(String sizeString, long defaultSize) {
		int multiplier = 1;

		if (sizeString.endsWith("K")) {
			multiplier = 1024;
		} else if (sizeString.endsWith("M")) {
			multiplier = 1024 * 1024;
		} else if (sizeString.endsWith("G")) {
			multiplier = 1024 * 1024 * 1024;
		}

		if (multiplier != 1) {
			sizeString = sizeString.substring(0, sizeString.length() - 1);
		}

		long size = 0;

		try {
			size = Long.parseLong(sizeString);
		} catch (NumberFormatException nfe) {
			log.warn("Invalid format for file size ('" + sizeString + "'). Using default.");
			size = defaultSize;
			multiplier = 1;
		}

		return (size * multiplier);
	}

	/**
	 * <p>
	 * Returns the path to the temporary directory to be used for uploaded files
	 * which are written to disk. The directory used is determined from the
	 * first of the following to be non-empty.
	 * <ol>
	 * <li>A temp dir explicitly defined either using the <code>tempDir</code>
	 * servlet init param, or the <code>tempDir</code> attribute of the
	 * &lt;controller&gt; element in the Struts config file.</li>
	 * <li>The container-specified temp dir, obtained from the
	 * <code>javax.servlet.context.tempdir</code> servlet context attribute.</li>
	 * <li>The temp dir specified by the <code>java.io.tmpdir</code> system
	 * property.</li> (/ol>
	 * </p>
	 * 
	 * @param mc
	 *            The module config instance for which the path should be
	 *            determined.
	 * @return The path to the directory to be used to store uploaded files.
	 */
	protected String getRepositoryPath(ModuleConfig mc) {
		// First, look for an explicitly defined temp dir.
		String tempDir = mc.getControllerConfig().getTempDir();

		// If none, look for a container specified temp dir.
		if ((tempDir == null) || (tempDir.length() == 0)) {
			if (servlet != null) {
				ServletContext context = servlet.getServletContext();
				File tempDirFile = (File) context.getAttribute("javax.servlet.context.tempdir");

				tempDir = tempDirFile.getAbsolutePath();
			}

			// If none, pick up the system temp dir.
			if ((tempDir == null) || (tempDir.length() == 0)) {
				tempDir = System.getProperty("java.io.tmpdir");
			}
		}

		if (log.isTraceEnabled()) {
			log.trace("File upload temp dir: " + tempDir);
		}

		return tempDir;
	}

	/**
	 * <p>
	 * Adds a regular text parameter to the set of text parameters for this
	 * request and also to the list of all parameters. Handles the case of
	 * multiple values for the same parameter by using an array for the
	 * parameter value.
	 * </p>
	 * 
	 * @param request
	 *            The request in which the parameter was specified.
	 * @param item
	 *            The file item for the parameter to add.
	 */
	protected void addTextParameter(HttpServletRequest request, FileItem item) {
		String name = item.getFieldName();
		String value = null;
		boolean haveValue = false;
		String encoding = null;

		if (item instanceof DiskFileItem) {
			encoding = ((DiskFileItem) item).getCharSet();
			if (log.isDebugEnabled()) {
				log.debug("DiskFileItem.getCharSet=[" + encoding + "]");
			}
		}

		if (encoding == null) {
			encoding = request.getCharacterEncoding();
			if (log.isDebugEnabled()) {
				log.debug("request.getCharacterEncoding=[" + encoding + "]");
			}
		}

		if (encoding != null) {
			try {
				value = item.getString(encoding);
				haveValue = true;
			} catch (Exception e) {
				// Handled below, since haveValue is false.
			}
		}

		if (!haveValue) {
			try {
				value = item.getString("ISO-8859-1");
			} catch (java.io.UnsupportedEncodingException uee) {
				value = item.getString();
			}

			haveValue = true;
		}

		if (request instanceof MultipartRequestWrapper) {
			MultipartRequestWrapper wrapper = (MultipartRequestWrapper) request;

			wrapper.setParameter(name, value);
		}

		String[] oldArray = (String[]) elementsText.get(name);
		String[] newArray;

		if (oldArray != null) {
			newArray = new String[oldArray.length + 1];
			System.arraycopy(oldArray, 0, newArray, 0, oldArray.length);
			newArray[oldArray.length] = value;
		} else {
			newArray = new String[] { value };
		}

		elementsText.put(name, newArray);
		elementsAll.put(name, newArray);
	}

	/**
	 * <p>
	 * Adds a file parameter to the set of file parameters for this request and
	 * also to the list of all parameters.
	 * </p>
	 * 
	 * @param item
	 *            The file item for the parameter to add.
	 */
	protected void addFileParameter(FileItem item) {
		FormFile formFile = new CommonsFormFile(item);

		elementsFile.put(item.getFieldName(), formFile);
		elementsAll.put(item.getFieldName(), formFile);
	}

	// ---------------------------------------------------------- Inner Classes

	/**
	 * <p>
	 * This class implements the Struts <code>FormFile</code> interface by
	 * wrapping the Commons FileUpload <code>FileItem</code> interface. This
	 * implementation is <i>read-only</i>; any attempt to modify an instance of
	 * this class will result in an <code>UnsupportedOperationException</code>.
	 * </p>
	 */
	static class CommonsFormFile implements FormFile, Serializable {
		/**
		 * <p>
		 * The <code>FileItem</code> instance wrapped by this object.
		 * </p>
		 */
		FileItem fileItem;

		/**
		 * Constructs an instance of this class which wraps the supplied file
		 * item. </p>
		 * 
		 * @param fileItem
		 *            The Commons file item to be wrapped.
		 */
		public CommonsFormFile(FileItem fileItem) {
			this.fileItem = fileItem;
		}

		/**
		 * <p>
		 * Returns the content type for this file.
		 * </p>
		 * 
		 * @return A String representing content type.
		 */
		public String getContentType() {
			return fileItem.getContentType();
		}

		/**
		 * <p>
		 * Sets the content type for this file.
		 * <p>
		 * NOTE: This method is not supported in this implementation.
		 * </p>
		 * 
		 * @param contentType
		 *            A string representing the content type.
		 */
		public void setContentType(String contentType) {
			throw new UnsupportedOperationException("The setContentType() method is not supported.");
		}

		/**
		 * <p>
		 * Returns the size, in bytes, of this file.
		 * </p>
		 * 
		 * @return The size of the file, in bytes.
		 */
		public int getFileSize() {
			return (int) fileItem.getSize();
		}

		/**
		 * <p>
		 * Sets the size, in bytes, for this file.
		 * <p>
		 * NOTE: This method is not supported in this implementation.
		 * </p>
		 * 
		 * @param filesize
		 *            The size of the file, in bytes.
		 */
		public void setFileSize(int filesize) {
			throw new UnsupportedOperationException("The setFileSize() method is not supported.");
		}

		/**
		 * <p>
		 * Returns the (client-side) file name for this file.
		 * </p>
		 * 
		 * @return The client-size file name.
		 */
		public String getFileName() {
			return getBaseFileName(fileItem.getName());
		}

		/**
		 * <p>
		 * Sets the (client-side) file name for this file.
		 * <p>
		 * NOTE: This method is not supported in this implementation.
		 * </p>
		 * 
		 * @param fileName
		 *            The client-side name for the file.
		 */
		public void setFileName(String fileName) {
			throw new UnsupportedOperationException("The setFileName() method is not supported.");
		}

		/**
		 * <p>
		 * Returns the data for this file as a byte array. Note that this may
		 * result in excessive memory usage for large uploads. The use of the
		 * {@link #getInputStream() getInputStream} method is encouraged as an
		 * alternative.
		 * </p>
		 * 
		 * @return An array of bytes representing the data contained in this
		 *         form file.
		 * @throws FileNotFoundException
		 *             If some sort of file representation cannot be found for
		 *             the FormFile
		 * @throws IOException
		 *             If there is some sort of IOException
		 */
		public byte[] getFileData() throws FileNotFoundException, IOException {
			return fileItem.get();
		}

		/**
		 * <p>
		 * Get an InputStream that represents this file. This is the preferred
		 * method of getting file data.
		 * </p>
		 * 
		 * @throws FileNotFoundException
		 *             If some sort of file representation cannot be found for
		 *             the FormFile
		 * @throws IOException
		 *             If there is some sort of IOException
		 */
		public InputStream getInputStream() throws FileNotFoundException, IOException {
			return fileItem.getInputStream();
		}

		/**
		 * <p>
		 * Destroy all content for this form file. Implementations should remove
		 * any temporary files or any temporary file data stored somewhere
		 * </p>
		 */
		public void destroy() {
			fileItem.delete();
		}

		/**
		 * <p>
		 * Returns the base file name from the supplied file path. On the
		 * surface, this would appear to be a trivial task. Apparently, however,
		 * some Linux JDKs do not implement <code>File.getName()</code>
		 * correctly for Windows paths, so we attempt to take care of that here.
		 * </p>
		 * 
		 * @param filePath
		 *            The full path to the file.
		 * @return The base file name, from the end of the path.
		 */
		protected String getBaseFileName(String filePath) {
			// First, ask the JDK for the base file name.
			String fileName = new File(filePath).getName();

			// Now check for a Windows file name parsed incorrectly.
			int colonIndex = fileName.indexOf(":");

			if (colonIndex == -1) {
				// Check for a Windows SMB file path.
				colonIndex = fileName.indexOf("\\\\");
			}

			int backslashIndex = fileName.lastIndexOf("\\");

			if ((colonIndex > -1) && (backslashIndex > -1)) {
				// Consider this filename to be a full Windows path, and parse
				// it
				// accordingly to retrieve just the base file name.
				fileName = fileName.substring(backslashIndex + 1);
			}

			return fileName;
		}

		/**
		 * <p>
		 * Returns the (client-side) file name for this file.
		 * </p>
		 * 
		 * @return The client-size file name.
		 */
		public String toString() {
			return getFileName();
		}
	}
}
